A conventional power transferring system for vehicle is shown in FIG. 1 and generally includes an engine 10a, a clutch 12a, a gearing and manual brake device 13a, a turbo compressor 16a and an air releasing valve for braking 17a which reduces the air supply to the engine and causes the un-complete combustion such that the compression force in the engine is used to brake the vehicle. The exhaust air is released via a catalyzer converter 18a and a muffler 19a. 
In the conventional power transferring system, the engine receives extra air from the turbo and this is affected only when the revolution of the engine is at mediate level and is useless when the vehicle starts from stationary status or when the high gear is shifted to low gear. There are two types of operation of the gearing device and the first one is manual operation and the second one is automatic operation. When shifting by manual, the torque drops immediately and the torque cannot be increased immediately. The automatic operation uses a torque converter to cooperate with the acceleration valve to maintain the toque. However, the temperature of the engine oil is high in the engine and this cause low efficiency of transmission. The heavier the load is, the higher the heat lost is. The conventional braking system causes high temperature when the braking device is operated frequently such as when the vehicle goes on a downward slope road. The air releasing valve for braking 17a does not work at high gear position with low revolution. Besides, the in-complete combustion generates problems related to air pollution.
The present invention intends to provide a gearing unit of a power transferring system wherein the revolution of each gear of the gearing unit can be increased to its maximum revolution. When the acceleration pedal is pushed, the output shaft is affected. When the acceleration pedal is released, the engine brake feature is performed.